A potential treatment for hypothalamic obesity that often afflicts
children who receive treatment for brain tumors or leukemia has been
discovered by researchers at St. Jude Childrens Research
Hospital. Many of these childhood cancer survivors die in adulthood
as a result of obesity and its associated diseases. Dieting and
exercise have no effect on this type of obesity, and until recently,
investigators have been unable to determine the cause of hypothalamic
obesity or find an effective treatment.

However, at the recent Pediatric Academic Society meeting, a new
study presented by clinicians from St. Jude shed light on the origins
of and medical treatment for this condition. It indicates that the
patients obesity is caused by the bodys inability to
adequately release insulin. It also indicates that this condition can
be treated with octreotide acetate (Sandostatin), a medication that
inhibits the release of excess insulin.

Obesity Linked to Damaged Hypothalmus

According to the study, when a child is treated for a brain tumor or
leukemia, either the tumor itself, surgery, chemotherapy, or
radiation injures the hypothalamus, causing the body to produce
excessive insulin.

"In early studies with rats, damage to a certain area of the
hypothalamus caused obesity, hyperphagia, and hyperinsulinism. But we
werent sure if the damage to the hypothalamus was having the
same effect in humans," said Robert H. Lustig, MD, associate
professor, University of Tennessee, consulting physician at St. Jude
Childrens Research Hospital, and author of the study. "We
also wanted to discover which came first: the obesity or the excess
insulin, and whether these problems could be treated."

Dr. Lustig and his team assessed eight patients (four male and four
female) 10 to 18 years of age with marked and worsening obesity that
began after therapy for leukemia or brain tumors. In each patient,
previous dietary restriction had not produced any weight loss, only
continued weight gain. Oral glucose tolerance testing showed normal
fasting glucose levels but mild glucose intolerance in five of the
eight patients. Fasting insulin levels were minimally elevated, but
peak insulin responses to glucose were markedly exaggerated in six patients.

Obesity--A Phenotype of Many Diseases

"Based on the data we collected in our initial research, we
administered increasing doses of octreotide, an insulin inhibitor,
for 6 months without dietary restriction," said Dr. Lustig. The
children in the study were given three injections of octreotide per
day for 6 months to a year. They responded with an average weight
loss of 11 pounds or with weight maintenance. Dr. Lustig says that
because damage sustained to the hypothalamus from the tumor or
treatment is permanent, these children will likely need to continue
this medication throughout their lives.

"This study increases our understanding of obesityin general,
said Dr. Lustig. "Our research gives more credence to the idea
that obesity is not one disease, but a phenotype of many
diseases, with different causes. This is significant because we have
developed a specific treatment for a specific type of obesity. If
other types of obesity can be discovered, other specific treatments
can also be developed."